Compressor-overload regulator



T. J. HART. COMPRESSOR OVERLOAD REGULATOR.

APPLICATION FILED AUG-7, I918.

Patented May 17, 1921.

,4 TTOR/VEY UNITED STATES PATENT OFFICE.

THOMAS J. HART, OF COBNING, NEW YORK, ASSIGNOR TO ING-ERSOLL-RAND COM- PANY, OF JERSEY CITY, NEW JEI RTSEY, A CORPORATION OF NEW JERSEY.

COMPRESSOR-OVERLOAD REGULATOR;

Specification of Letters Patent.

Patented May 17, 1921.

Application filed August 7, 1918. Serial No.'248,811.

- Corning, in the county of Steuben and tate of New York, have invented a certain new and useful Improvement in Compressor- Overload Regulators, of which the following is a specification.

This invention relates to compressors, and in particular to a compressor utilized for compressing natural gas for the extraction of gasolene. More especially the present invention relates to a compressor for this purpose provided with a regulator in the form of an equalizer to prevent a change in intake pressure due to increased pressure within the well or other contained source from which the gas is drawn from unduly over-w loading the compressor.

The objects of the present invention are to provide an equalizer for this type of compressor which will be compact, cheap, simple and efiicient and which will also prevent loss of gas.

In the process of extracting gasolene from natural gas the gas as it is pumped or flows from the well is passed through a compressor, usually one having two or three stages, the discharge pressure of the gas after passing through the compressor being in the neighborhood of from two hundred pounds to three hundred pounds, the gasolene contained within the natural gas being precipitated from the intercooler between the high pressure stages or from the high pressure discharge line. In this type of compressor the absolute pressure within the gas well fluctuates 'withln wide limits and at times is several hundred per cent. greater than at other times, which, if not compensated for will greatly overload the compressor when the pressure within the well rises above normal. To prevent this overloading by simple means is accomplished in the manner brought out in the following description. I a

In the drawings annexed hereto and forming a part hereof,

Figure 1 shows diagrammatically a multistage compressor provided with the present form of equalizer; and

Fig. 2, a diagram showing the effect of variations of intake pressure of the gas being compressed upon the amount of compression in each of the cylinders of the compressor..

Referring more particularly to the drawmgs, 1 refers to the low pressure or vacuum cylinder of a multi-stage compressor, and 2 the intercoolerbetween the cylinder 1 and intermediate cylinder 3. In this figure a.

third or hi h pressure cylinder is shown diagrammatically at 4 in alinement with the cylinder 3 and having an intercooler 5 interposed between it and the cylinder 3.

The intake 6 of the compressor which is in direct connection with the gas well serves to admit the gas into the cylinder 1. It is obvious that with the intake 6 connected with a large space filled with gas a distance from the compressor and at great distances below the surface of the ground that the pressure therein will vary very greatly and if the pressure increases will allow a greater mass of gas to enter the cylinder 1 with correspondingly increased work put upon the compressor. If the pressure within the well and consequently in the intake 6 is increased the amount of work may be greatly in excess of the capacity of the compressor so that an equalizer must-be provided to keep the work of the compressor balanced and within its normal capacity without unloading the units. For this purpose a bypass conduit 7 is provided connecting the discharge side of the low pressure cylinder 1 at the point it joins the intercooler 2with the intake 6. 'Within this bypass conduit 7 is located a valve body 9 having a valve member 10 held against its seat by means of a compressive spring 11 the pressure of which against the valve 10 may be regulated by means of a wheel 12.

In the operation of the compressor, the increase in the intake pressure 6 will cause a corresponding increase in the pressure in the discharge at' 8 and also in the intercooler 2 until a point is reached when the discharge pressure in 8 and in the intercooler 2 is sulficient to overcome the pressure-of spring 11 in the valve body 9 which will cause the valve 10 to open and allow the excess gas to flow back into the intake 6. In this manner the load on the compressor is kept from exceeding a given maximum and the excess gas is returned to the intakewithout loss and without unloading the compressor, Also, should the valves in the intermediate other cylinders as shown and high pressure cylinders of the coinpressor become inoperative or leak, thus causing gas to leak back into the intercooler 2, the valve 10 will come into operation to prevent the compressor cylinderbecoming overloaded. The force of the spring 11 may readily be varied by means of the wheel 12 so that the valve 9 will open at any pressure for which it is set and for which when the intake is at normal pressure. As. seen by these areas 13, 14, 15, the Work done. 1n each cylinder is approximately equal:

With an increase in intake pressure the work done in the cylinders r stages is represented by the areas 16, 17 and 18, included within the fine lines. From these it will be seen that the work required of the low pressure cylinder represented by area 16 is far greater than that normally required as represented by area 13, and also greatly in excess of strength. The Work required by the by a comparison of areas 17 and 14, and 18'and 15 shows thatthe work done in the intermediate cylinder is greatly enlarged but not to the same extent as the work of the low pressure cylinder. I 1

In further explanation of Fig. 2,'it.may

' be said that in said figure ordinates represent pressures and the abscissae represent the length of stroke as usual. The base is taken as absolute pressure and the line 20 The sec-.

indicates atmospherlc pressure. tioned area 13 as stated represents the diagram with a minimum or normal intake pressure, while the dotted lines 21 indicate the desirable diagram with a somewhat higher intake pressure.

The diagram indicated by the 'full'lines 16 would be approximately obtained without control of the intake pressure. As shown,

the pressureJvouLd rise from about the point 22, which indicates approximately the outlet pressure desired, and the arrow pointed line 23 extending between the points 22 and 24 serves to indicate graphically the difierence between the diagram 21 in dotted lines and the diagram 16 in full lines.

As stated, the sectioned area -14 represents the diagram in the second stage with a normal intake pressure and the area 15 represents the normal diagram in the third stage. The areas 17 and 18 in full lines indicate the diagrams in these stages corresponding to the diagram 16 in the first stage with increased intake pressure and no regulation. The lines 25, 26, 27, 28 and 29 show diagrammatically the proportionate work done in each stage at the different pressures, because in each rectangular area formed by said lines the work diagrams are indicated.

From the above description and explanation it Will be seen that a simple and efiicient equalizer has been devised which will limit the work accomplished by the compressor in order to prevent an overload beyond the capacity of the compressor and keep the machine balanced.

It is to be understood that the present showing and description discloses only one specific embodiment of the present invention and that other forms and modifications are included within the spirit and scope of the invention, as expressed in the appended claim.

What I claim is:

A regulating system for producing a constant quantity of discharge from the'high pressure cylinder of a compound compressor without varying the speed or unloading the machine, in which .both the intake and the discharge pressures are variable, comprising a lowpressure cylinder, an intercooler, and at least one high pressure cylinder, a bypass from the intercooler to the intake of theloW pressure cylinder, and a pressure relief valve in said by-pass, adapted to open THOMAS J. HART. 

